When you open the database, you will find that:

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| backup_operation   |
| information_schema |
| operation          |
+--------------------+
3 rows in set (0.09 sec)

mysql> use operation;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed

Load table and column names to complete the table information

You can turn off this feature for faster startup using option: – A

To put it bluntly, you can add a – a option to the login database without pre reading the database information

The following reasons are found on the Internet:

The reason for the problem is::
       We entered mysql without using the -A parameter.
       That is, we use
           mysql -hhostname -uusername -ppassword -Pport to access the data, the
       instead of using
           mysql -hhostname -uusername -ppassword -Pport -A to access the database.
 
           When we open the database, i.e., use dbname, we have to pre-read the database information, and when we use the -A parameter, we do not pre-read the database information.
 
The key factor is that your database gets bigger. The system becomes slower

There is another case:

When accessing the database today:

Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Generally, this problem occurs because the database in MySQL is too large, resulting in too long read ahead time, thus displaying this prompt. If this problem has not been encountered before, then the cause of this problem may be due to the operation of changing database information, such as dropping a large table (tens of millions of data) and terminating halfway

First, check the current process

mysql> show processlist ;

If the ID of the lock table in the figure above is 16545618, you can use the kill command to end it

mysql> kill 16545618;

If I delete these lock tables, my MySQL will be able to access them normally